Conventionally, an insert-molded article, that is a resin molded metal component, have been widely used for a package for an electronic component, etc. The insert-molded article is usually manufactured by punching out the lead frame from a hoop material in a state where the metal component and a runner are connected by tie bars, setting the lead frame in a mold, injecting resin to resin-mold and the metal component, subsequently taking out the lead frame from the mold, and separating the insert-molded article from the lead frame by cutting the tie bars.
In the method of manufacturing an insert-molded article mentioned above, however, it is necessary for tie bars to be removed from the lead frame taken out from the mold by cutting in another process, and thereby, more working hours are required and a mold for a single purpose of being cut is required, thus resulting in increased equipment cost.
In order to address such a problem, a method of setting a lead frame in a forming mold, and cutting tie bars with cut means provided to the forming mold, while molding a metal component in the lead frame with resin at the same time, is proposed in Patent Document 1. Since, in this case, resin molding and tie bar cutting can be performed in a single process, not only working hours but also equipment cost can be decreased.    Patent Document 1: Japanese Unexamined Patent Application Publication No. 2000-289059